High intensity short-arc lamp having bi-metallic electrode leads



N. C. BEESE SITY SHORT-ARC LAMP HAVING ADS HIGH INTEN BI-METALLIC Filed April 18, 1967 ELECTRO Oct. 22,

lNVE-NTOIZ NORMAN C. BEESE BY ATTORNEY ,MJ-A-JQ United States Patent 3,315,116 HIGH INTENSITY SHORT-ARC LAMP HAVING I BI-METALLIC ELECTRODE LEADS Norman C. Beese, Verona, N.J., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Oct. 22, 1965, Ser. No. 502,705 4 Claims. (Cl. 313-217) Thisinvention relates to electrical discharge lamps and more particularly to high pressure, high current, gas or vapor discharge short-arc lamps which are constructed to provide desired acoustical resonance properties to be operative in optical communication systems.

Lamps of the short are type are known to the prior art and in general are constructed of a material capable of withstanding high temperatures and to provide a chamher for gases, such as argon, xenon, neon, etc., alone or with mercury or other vapor additives, and within which are located electrodes for forming the arc. Such lamps are shaped to provide a central bulbous section in which the cathode and anode electrodes are located and communicating end sections in which cathode and anode conductor materials arelocated for supplying power to the electrodes. It is known that improved operation of this type lamp is elfected when the conductor materials include thin molybdenum ribbon structure but in order to protect the ribbon structure, it is conventional practice to seal this material in elongate vacuum spaces formed in the en dsections of the lamps. The vacuum spaces prevent damage to the ribbon structure by oxidation which would otherwise occur by air entering through the end extremities of the lamps. However the provision of the elongate vacuum spaces results in lamps of substantial overall length.

The present invention concerns the above general type of short are lamp utilizing ribbon conductor structure but is directed to lamp construction wherein the usual vacuum spaces are eliminated and get results in a lamp of reduced overall length having high operating efiiciency.

One object of the present invention is to provide a high pressure short arc lamp utilizing ribbon conductors which oxidize at relatively low temperatures and which are arranged in the end sections of the lamp in a manner to prevent their oxidation under operating temperatures.

Another object is to provide a high pressure short are lamp which permits the utilizing of molybdenum ribbon conductors by arranging platinum conductors in the lamp end sections in a manner to prevent oxidation of the molybdenum conductors.

Other and more detailed objects of the invention will become apparent from a better understanding of the invention, which may be had from the accompanying drawings and description thereof.

FIGURE 1 is a longitudinal sectional view of a short arc lamp embodying the details of the present invention.

FIGURE la is a sectional view of a portion of FIG- URE 1 to show details.

FIGURE 2 is an enlarged cross sectional view taken on the line 2-2 of FIGURE 1 during the assembly of the lamp.

FIGURE 3 is an enlarged cross sectional view taken on the line 33 of 'FIGURE 1 during the assembly of the lamp.

FIGURE 3a is a view similar to FIGURE 2 at the final construction of the lamp.

Referring to FIGURE 1, the short are lamp indicated generally at 10 is preferably constructed of clear fused quartz to provide strong wall structure for withstanding the high temperatures and presures encountered during 3,3 15,1 16 Patented Apr. 18, 1967 2 operation. The lamp is shaped to provide a bulbous section 12 located between end sections 14-14 which are arranged to respectively provide the anode and cathode portions of the lamp. The cathode electrode is indicated at 16 and the anode electrode is indicated at 118 and conductor means is located in each end section of the lamp for the transmission of current to the anode and cathode electrodes.

The cathode 116 is formed of tungsten rod having the electrode end 16 disposed Within the bulbous section 12 and its shaft end 20 is received, as shown, in the inner end of a quartz coupling block 22. The coupling block 22 mounts in its outer end, the inner end of a nickel chrome plated brass or similar conductor 24 which has its outer end connected to a base cap 25. Ihe anode 18 is also formed of a tungsten rod having its shaft 26 received in the inner end of a quartz coupling block 28 which receives in its outer end, the inner end of a nickel chrome plated brass or similar conductor 30 which has its outer end connected to base cap 32.

The conductor means for supplying current to the cathode and anode are similarly arranged in the cathode and anode sections of the lamp and only a detailed description of the arrangement for the anode section .14 will be provided, although the similar structure is shown in connection with the cathode and is identified by prime numerals.

In the anode section 14, the ribbon conductors or strands are formed of a molybdenum section 40 which is mounted on the coupling 28 inwardly of its outer end and has its inner end "42 connected to the anode shaft 26 by means of a collar 43. A platinum ribbon section 4 4 is mounted on the coupling 28 about its outer end and has its inner end joined, for example, by spot welding indicated at 45 to the outer end of the molybdenum section 40. The ribbon strands are preferably formed of flat strips.

The outer end of the platinum section 44 is not identified but is secured between an inner collar 46 and an outer collar 48, as shown, which are preferably formed of brass, and are mounted on the conductor 30. After assembling, silver solder is applied in the zone indicated at 50 to interconnect the conductor 30, platinum ribbon 44 and the collars 46 and 48. The collar 48 provides an end space with the end of the lamp structure 10 and is provided with an exterior groove 52. A band 54 has an inner flange which is received in the groove 52 and provides a longitudinal space with the lamp structure and a packing medium which, for example, may be asbestos 58, fills the spaces and provides a thermally insulated cushioning zone for the end of the lamp. A clamp 60 is secured about the band 54 and the end plate 32 is secured to the collar 48 by suitable connectors 62.

In FIGURE 2, four platinum ribbons 4 4 are shown spaced circumferentially of the collar 48 and extend lengthwise of the coupling block as shown in FIGURE 1. These ribbons have relatively greater thickness than the molybdenum ribbons 44, as shown in FIGURE 3, when they are initially assembled and before the various lamp elements are compressed or fused together as shown in FIGURE 3a. It will be understood that the sectional View of FIGURES 2 and 3 show the various elements and materials in their relative positions before the elements and materials are compressed and fused together. As shown in FIGURES 2 and 3, the platinum ribbons have tapered or feathered edges 70 in order to reduce or prevent capillary paths or cracks from being formed in the quartz lamp structure at the final construction or fusion of the lamp elements. This is for the purpose of minimizing the passage or diifusion of air or oxygen into the molybdenum ribbon section which oxidizes substantially more readily than the platinum section.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood .that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

I claim:

1. In a short arc gaseous discharge lamp comprising a light transmissive central gas chamber located between an open end cathode section and an open end anode section each of which has a nonconductor coupling block mounting an outer elongate conductor shaft and an inner elongate conductor shaft and wherein each inner conductor shaft has a main electrode which is disposed in the central chamber and the electrodes are in spaced relation to provide a discharge are therebetween, the improvement which comprises,

(a) a plurality of ribbon conductor strands extending longitudinally of the conductor block and having means securing their outer ends in conducting relation with the outer conductor and other means securing their inner ends in conducting relation with the inner conductor,

(b) said conductor strands being formed of a front portion of readily oxidizible molybdenum material and a rear portion of platinum material which is relatively less oxidizible,

(c) closure means for the open ends of the sections and ((1) means to minimize the admission of air between the closure means and the rear portion of the strands. 2. The improvement of claim 1, further characterized by the v (a) conductor strands being in fiat sheet form and the platinum material being of substantially relatively greater thickness than the molybdenum material and also having tapering side edges. 3. The improvement of claim 1, further characterized by the (a) closure means providing a space at the end of each section and about the rear portion of the conductor strands which contains asbestos packing material to minimize the admission of air. 4. The improvement of claim 1, further characterized by the (a) means securing the outer ends of the conductor strands comprising inner and outer collars on the outer conductor shafts and a silver solder c0nnec tion between the collars.

References Cited by the Examiner UNITED STATES PATENTS 2,123,015 7/1938 Marden 313-217 2,735,954 2/ 195'6: Rawls 313217 2,781,470 2/ 1957 Bellott 313217 3,154,713 10/1964 Beese 313-217 JAMES W. LAWRENCE, Primary Examiner.

S. D. SOHLOSSER, Examiner. 

1. IN A SHORT ARC GASEOUS DISCHARGE LAMP COMPRISING A LIGHT TRANSMISSIVE CENTRAL GAS CHAMBER LOCATED BETWEEN AN OPEN END CATHODE SECTION AND AN OPEN END ANODE SECTION EACH OF WHICH HAS A NONCONDUCTOR COUPLING BLOCK MOUNTING AN OUTER ELONGATE CONDUCTOR SHAFT AND AN INNER ELONGATE CONDUCTOR SHAFT AND WHEREIN EACH INNER CONDUCTOR SHAFT HAS A MAIN ELECTRODE WHICH IS DISPOSED IN THE CENTRAL CHAMBER AND THE ELECTRODES ARE IN SPACED RELATION TO PROVIDE A DISCHARGE ARC THEREBETWEEN, THE IMPROVEMENT WHICH COMPRISES, (A) A PLURALITY OF RIBBON CONDUCTOR STRANDS EXTENDING LONGITUDINALLY OF THE CONDUCTOR BLOCK AND HAVING MEANS SECURING THEIR OUTER ENDS IN CONDUCTING RELATION WITH THE OUTER CONDUCTOR AND OTHER MEANS SECURING THEIR INNER ENDS IN CONDUCTING RELATION WITH THE INNER CONDUCTOR, (B) SAID CONDUCTOR STRANDS BEING FORMED OF A FRONT PORTION OF READILY OXIDIZIBLE MOLYBDENUM MATERIAL AND A REAR PORTION OF PLATINUM MATERIAL WHICH IS RELATIVELY LESS OXIDIZIBLE, (C) CLOSURE MEANS FOR THE OPEN ENDS OF THE SECTIONS AND (D) MEANS TO MINIMIZE THE ADMISSION OF AIR BETWEEN THE CLOSURE MEANS AND THE REAR PORTION OF THE STRANDS. 